CS0-003 Incident Response and Management Practice Question
This CS0-003 practice question tests your understanding of incident response and management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which TWO of the following are indicators of potential data exfiltration via DNS?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
High volume of TXT record queries
Option D is correct because TXT records are commonly used in DNS tunneling to encode exfiltrated data. Attackers embed data in TXT record queries or responses, and a high volume of such queries is a strong indicator of data exfiltration via DNS.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
This suggests HTTP-based C2, not DNS exfiltration.
✗
Large number of NXDOMAIN responses
Why it's wrong here
Indicates non-existent domains, not necessarily exfiltration.
✓
High volume of TXT record queries
Why this is correct
TXT records are commonly used to encode exfiltrated data.
Related concept
Read the scenario before looking for a memorised answer.
✓
Frequent queries to long subdomains
Why this is correct
Long subdomains are used to hide data in DNS queries.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction between DNS tunneling indicators (TXT record volume and long subdomains) and other DNS anomalies like NXDOMAIN responses, which are more associated with DGA or reconnaissance rather than exfiltration.
Detailed technical explanation
How to think about this question
DNS tunneling works by encoding data into DNS queries (often using TXT records) and sending them to a malicious authoritative DNS server, which decodes the data. The high volume of TXT queries and queries to long subdomains (e.g., base64-encoded data as subdomain labels) are classic signs of this technique, as normal DNS traffic rarely exhibits such patterns. Tools like dnscat2 and Iodine exploit this by using TXT records for bidirectional data transfer.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CS0-003 question in full detail.
Incident Response and Management — This question tests Incident Response and Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: High volume of TXT record queries — Option D is correct because TXT records are commonly used in DNS tunneling to encode exfiltrated data. Attackers embed data in TXT record queries or responses, and a high volume of such queries is a strong indicator of data exfiltration via DNS.
What should I do if I get this CS0-003 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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